Here are mine: (first 3 are almost equal for long days on the bike)
1. Progressive fork springs (lifted the front of bike back up and improved ride considerably)
2. Memphis Fats windshield (extends comfort immensely, modify mount to lean back close to face)
3. Mustang saddle with backrest (stock saddle is POS)
4. Clayton mod on stock pipes (acceptable sound without spending much money, easy to do)
5. Extenders to move the bars back (relieves back pain)
6. Cobra Fatty engine guard (many new foot rests)
7. Kuryakyn Highway pegs (feels so good)
8. Saddlebags (to carry critical gear)
9. Vista throttle lock (gives the throttle hand a break)
10.Cargo box mounted on luggage rack (waterproof touring necessity, but instantly removable)
11. Lowers for windshield (improves airflow over knees, reduces blast into chin and helmet shake)
12. Engine guard chaps (keeps feet warmer in cold weather, but goofy looking)
13. Cut off rear of shifter (in my foot's way and not used anyway)
14. Kuryakyn grips and bosses (better feel)
15. Windshield tri-pouch for the little things (camera, binocs, etc)
16. Handlebar Ram mounts for cellphone, iPod, etc)
17. Rack on lid of trunk for quick access to All-weather suit.
My bike is for touring. My mods are oriented for that purpose, all mods fixed a problem.
The bike is complete now and ready for most extended or everyday asphalt adventures.
I thought this info might be helpful for new owners and very interesting to experienced owners.